Engaging and disengaging device for presses, stamping machines, and similar machine tools



May l, 1934. 4 wl sCHMlD-r l l 1,956,658

ENGAGING AND DISENGAGING DEVICE Eon PREssEs, STAMPING MACHINES, AND'SIMILAR MACHINE Toons Filed July 16. 1932 I l f l /NvENTQ/ n//L//fm Se f//WDT HTToz/VEY Patented May 1, 1934 UNITED STATES PATENT OFFICE PRESSES, STAMPING MACHINES,

SIMILAR MACHINE TOOLS AND Wilhelm Schmidt, Erfurt, Germany Application July 16, 1932, Serial No. 622,995 In Germany October 11, 1930 1 Claim. (Cl. 'X8-39) This invention refers to forging presses and relates more particularly to coining, punching, embossing and shaping presses used for cutting or compressing metals, such as iron,vcopper, alu-4 5 minum and its alloys.

In the ordinary presses, stamping machines and similar machine tools running with 20 to 30 strokes per minute claw or rotary wedge clutches are generally employed for engaging and l disengaging the drive of the aperture holder. 'I'hese have proved satisfactory for such stroke speeds.

However for many machine tools 100 and more strokes per minute are necessary. At these speeds claw clutches do not engage reliably as they require long engaging times. Further jars occur which lead to premature wear of the claw clutches.

The object ofthe invention is to produce in- :0 stead of these clutches a device which ensures reliable and perfect engagement and disengagement at high stroke speeds.

The inventive idea consists in that between the upper tool holder and the drive, for example the g cam shaft, a toggle lever is arranged which can articulate out of its straight line position towards both sides of its longitudinal axle and which is bent by a control mechanism, for example a compressed air cylinder, spring or the like during 0 idle running every time towards one side of its longitudinal axis, the upper tool holder being held in its highest position by compressed air cylinders or springs. However, when the machine is working a bending of the toggle lever 5 Atowards this side is prevented by the controlling mechanismand causes it to bend into a rigid position towards the opposite side of its longitudinal axis which position is ensured by two oppositely situated abutments on its rods so that the upper tool holder descends, and is pulled back into its initial position by thedrlve.

Toggle levers are already known in hydraulic presses. However, these toggle levers serve for rapidly covering the idle stroke, that is the stroke from the highest position to that in which the tool rests on the work piece. After this idle stroke the hydraulic cylinder proper becomes operative for effecting the work. The engagement and disengagement of the toggle lever serves D therefore in this instance only for accelerating as far as possible the idle travel before commencing the work. For this purpose two toggle levers with suitable intermediate levers and controls are necessary. i However according to the invention only one toggle lever is employed which forms an extremely simple drive for ,the upper tool holder and ensures a reliable engagement and disengagement at high running speeds without the known jolts and wear occurring as in the case of claw 80 clutches.

An embodiment of the invention is illustrated by way of example in the accompanying drawing in which:-

Fig. 1 shows the machine with toggle lever and controll in idle running position.

Fig. 2 shows the machine with these arrangements in operative position.

,In a machine frame 1 the cam or crank shaft 2 is journalled in known manner and a continually rotating fly wheel 3 is keyed on this shaft. An upper tool holder 5 reciprocates vertically between guides 4 4.

The upper tool holder 5 is connected to the cam or crank shaft 2 by a toggle lever 6 composed of two rods 7 and 8. The rod 7 is hingedly connected to the shaft 2 at 9, whereas the rod 8 is articulated at 10 to the upper tool holder 5. The tool rods 'l and 8 are interconnected in the elbow joint 11. The rod 7 also carries an abutment 12 and the rod 8 a corresponding abutment 13 which abutments are in contact when the drive is in operative position (Fig. 2).

In this position the elbow joint l1 is situated slightly laterally of the centre line A, B in order in conjunction with the two abutments 12, 13 to prevent a folding back of the toggle lever 6, 7, 8. In the idle running position shown in Fig. 1 the elbow lever is situated on the other side also slightly out of the centre line A, B to ensure a reliable bending. A rod 14 of the control mechanism is articulated in the elbow joint 11. This rod 14 carries at its other end a piston 15 which is reciprocable in a pressure cylinder 16. The piston 15 is controlled by a valve 17 which can be shifted by means of a band lever 18 or mechanically from the machine drive in the idle running position (Fig. 1) or the operative position (Fig. 2) of the machine. The pressure cylinder is hingedly connected to a joint 19 on the machine frame. 1 to follow the movements of the piston 15 in the pressure cylinder 16 and also those of the control rod 14, the toggle lever 6 and the upper tool holder 5.

The upper tool Aholder 5 is held in its uppermost position by a pressure medium drive during the idle running of the machine. However, when the machine is working this pressure medium drive yields and allows the upper tool holder to descend to perform its work. One or, according to Fig. 1 of the drawing, two rods 22, 23 hingedly connected to the upper tool holder 5 at 20 and 21 respectively may serve as pressure medium drive, each of these rods 22 and 23 being connected to pistons 26 and 27 respectively, reciprocating each in a compressed air or a hydraulic cylinder 24 or 25. Instead of this arrangement one or more springs with abutments or other similar means might be employed.

The operation is as follows:

During the idle running of the machine the parts are in the position shown in Fig. 1. The fly wheel 3 and the cam vor crank shaft 2 rotate continually.

When the valve 17 is in the position shown in Fig. 1 the pressure medium flows into the cylinder space 16a and exerts pressure on the piston 15 in the direction towards the elbow joii. 11. During each rotation of the cam or crank shaft from its upper dead centre position into its lower dead centre position the toggle lever 6 bends at the elbow joint 11 so that the two rods '7 and 8 assume a position substantially as indicated in dotted lines in Fig. 1. During this movement the elbow joint 11 describes an arc with the joint 10 around the centre, thereby travelling from 1l to 11a. During this bending movement the control rod 14 and also the piston 15 in the cylinder 16 shift towards the elbow joint position 11a, thereby correspondingly oscillating the cylinder on its joint 19. y During the rotation of the cam or crank shaft 2 from its lower dead centre position into its upper dead centre position the toggle lever is extended until it assumes the position shown in full lines at Fig. 1, whereby the elbow joint travels from 11a back to 11 and the control lever 14 is correspondingly pushed back with the piston 15. As, during the idle running, the upper tool holder 5 must not descend, it is held in its raised position by means of the rods 22, 23 acted upon by the pistons 26, 27. The pistons 26, 27 in their highest position in the cylinders 24, 25 determine at the same time the highest position of the tool holder 5.

When the machine is to operate, the control valve 17 is shifted into the position shown in Fig. 2 by hand or mechanically by the drive of the machine. The pressure medium then flows into the cylinder space 16 and acts on the opposite side of the piston 15 to that acted upon during the idle running according to Fig. 1. Thus the piston 15 and consequently the control rod 14 are shifted in the direction of the arrows (Fig.

2) until the elbow joint 11 and the rods 7, 8 reach the rigid position 11b shown in Fig. 2.

They prevent the toggle lever 6, 7, 8 from being further folded in the direction of movement of the piston 15 and the control rod 14 according to Fig. 2. During the rotation of the cam or crank shaft the toggle lever no longer bends but remains rigid and, owing to the action of the pressure medium on the piston 16, can no longer bend in the direction indicated in Fig. 1, owing to the pull exerted by the control rod 14, but its rods 7 and 8 remain with the elbow lever in the position 11b. Consequently the upper tool holder will now be pressed downwards to effect its work by the cam or crank shaft 2, overcoming the upward pull of the pistons 26, 27 and rods 22, 23. After the termination of the working stroke the upper tool holder 5 is again drawn upwards by the toggle lever 6, '7, 8.

If the machine is to run idle it is merely necessary to set the control valve 17 from the position shown in Fig. 2 into that according to Fig. 1 so that the elbow joint shifts from the position 1lb into the position 11.

By means of the engaging and disengaging device according to the invention a reliable engaging and disengaging of the drive of the upper tool holder 5 is also ensured at high running speeds and all detrimental jolts and jars are avoided.

I claim:

An engaging and disengaging device for presses, stamping machines and similar machine tools, comprising in combination an upper tool holder, a work holder to be operated upon by said tool holder, a driving means to actuate said upper tool holder, a crank and toggle connection between said upper tool holder and said driving means, said toggle connection being broken when the driving means is not actuating the upper tool holder and being straightened when the toggle connection is operating the upper tool holder, means to break said toggle connection and to straighten said toggle connection, releasable fluid actuated means for holding the upper tool holder in operative position removed from the Work holder when the toggle connection is broken, said crank and toggle connection operating said upper tool holder when the toggle connection is in straightened position against the force exerted by said releasable fluid actuated means.

WILHELM SCHMIDT. 

